Heritage Action, the group campaigning for the protection of threatened heritage sites, has challenged English Heritage’s plans for the future of Silbury Hill in Wiltshire.

The largest prehistoric mound in Europe, Silbury Hill was built between 2800 and 2000BC but in May 2000 a large hole appeared after a period of heavy rainfall made an old excavation shaft collapse.

In a report issued on July 18 2005 English Heritage outlined their plan to repair the damage by re-entering the mound through a tunnel from a previous excavation. They would then remove the existing collapse and inadequate backfill in the tunnel and backfill it properly.

The report stated: “The work would be accompanied by an archaeological investigation programme which would fully record all the parts of the hill which are exposed again and enhance our knowledge of its construction.”

In response to these proposals, however, Heritage Action has called on English Heritage to explain its decision.

“On the basis of the risk assessment that English Heritage has presented, tunnelling appears to be by far the least appropriate of the repair options,” said the pressure group in a statement on its website.

“Yet that is what English Heritage have decided will happen. The public must be told what has led them to this choice.”

Heritage Action said that if tunnelling is proven by engineers to be the best way to tackle the problem then it would accept this solution, however they expressed their concerns about this approach.

“If career-boosting research is the 'treasure' to be won by selecting the most damaging solution, then our generation would be no better than the treasure-seeking vandals of old whose tunnels caused the problem,” it said.

The campaign group has called for clarification of the reasoning behind the plans and a public consultation meeting.

As previously reported on the 24 Hour Museum, there has been intense debate about the best way to repair the damage on Silbury Hill and preserve the site for the future.

According to their recent announcement, English Heritage has stated that it, “has carried out extensive investigations into the condition of the hill and research as to the best way forward to preserve its long term stability."

English Heritage have proposed a scheme to restore the hill but campaign group Heritage Action has expressed concerns about the plans.

“This work outlined a number of options for the future of the hill, one of which has now been selected by English Heritage for further exploration and feasibility studies. English Heritage consulted with a wide group of interested parties before the decision was taken, and presented three main options for discussion at a seminar for local and national archaeology experts in September 2004.”

However, Heritage Action still has its doubts about the plans and believe an alternative technique called grouting has not been fully explored. Speaking to the 24 Hour Museum, Nigel Swift from the group explained: “It may not completely fill it but it is a minor problem compared to the damage that tunnelling could cause.”

“The detailed data which they have published on the relative merits and the relative damage arising from each of the options suggests very strongly that tunnelling will cause the most collateral damage. All we require is for them to explain that to the public,” he added.

English Heritage said they would look into Heritage Action’s concerns although they were unable to make an immediate comment.